3 cylinder crankshaft

[solo1]

ello' scholars, for our midterm project were required to do an engine piston and crank assembly. I've finished all the pieces required but the 3 cylinder crankshaft.

From the picture, I've started from the "B" side and will go to "A" then C eventually.

 

After drawing and extruding the first 2 cylinders on the end, its time to do the ellipse at a 45 degree angle downward to the right. I don't know exactly how to use the ellipse dimensions given to make the part accurate. As of now, I manually drew 2 circles at a 39 mm apart from eachother then created my ellipse around it.

 

Any tutorials or help would be lovely.

 

my attempt:

[Bishop]

You already appear to have done it the way I'd do it ... why can't you just do the same thing again?

[solo1]

I could do it again, but I dont believe it is dimensionally accurate. Is it really that simple? From the top right diagram you see that in the ellipse, the 2 cyclinders in each ellipse are overlapping eachother a bit. Each cylinder's diameter is 39. I figured the 25.5 minor, and 36.5 major dimensions would be relevant to creating the ellipse, but I didn't use that at all. What is the signficance of these 2 dimensions?

[JD Mather]

The dimension is a bit of a fudge do to rounding off for drawing board. (we couldn't make perfect geometry back then)

In a CAD program you can make the ellipse Tangent for blend into cylinder.

 

Attach your file here and then I'll attach my solution. (oops - I just realized my rod journals are not 120° apart. I'll need to fix that.)

 

 

This is the only example I have that is a good and ligitimate use of Move Face and also good use of Rotate Body.

[JD Mather]

Well that was fun.

I noticed your sketches aren't constrained - you might start here

http://home.pct.edu/~jmather/skillsusa%20university.pdf

Your Chamfer is in the wrong location as well.

 

Oops - still wrong, back in a few.

 

now i have it

 

Edited November 8, 2012 by JD Mather

[solo1]

Mather, I think I've got it. I used constraints this time. Someone please correct me on my set-up if there's an error..

[solo1]

whoops made a mistake last time..

 

 

correct one ^^^

Edited November 12, 2012 by solo1